Pipettes are used in conventional blood analyzers, by placing them in a support that fixes them relative to a test element onto which liquid is to be dispensed. That is, the dispensing tip of the pipette needs to be at a nonvarying predetermined distance from the test element, and appropriately centered, during the dispensing step. The conventional support has featured a stand having an aperture therein which preferably includes a keyway, and a key on the pipette is designed to loosely fit within the keyway. A tight fit is not needed, since gravity maintains the pipette against a stop to achieve the desired vertical height from the test element, and only gross rotational misadjustment in the X-Y plane need be prevented by the key and keyway interaction. An example of such a pipette and pipette support is shown in EPO Publication No. 278,144.
Such pipette supports normally are quite satisfactory and effective. However, because they do rely on gravity to fix the pipette in the "Z", or vertical, direction, they are insufficient when used in microgravity or zero gravity environments, such as in a space station. That is, the loose fit of the pipette along the Z axis within the pipette stand means that any accidental jarring can cause the pipette to (a) leave its stop and lose the desired "height" distance, that is, the distance from the test element, not to mention (b) leave the vicinity of the support entirely as a flying object.
Furthermore, even in 1G environments the loose fitting support can still provide too much potential misadjustments, particularly if tolerances are not followed during manufacturing, or if the chemistries being analyzed require unusually accurate positioning of the pipette, or if greater accuracy of analysis is desired. Close tolerances are too costly to maintain anyway, so the risk of a sloppy fit always remains.
Thus, there has been a need, prior to this invention, to have a pipette support that more positively engages the pipette.